Process for the manufacture of a glass fibre-reinforced plastics article and a glass fibre paste or slurry for use in the process

ABSTRACT

The process comprises mixing chopped glass fibres with plastics-forming ingredients and moulding or forming the mixture to obtain reinforced plastics articles. The invention lies in the use of chopped glass fibres in filamentary form. Conveniently the glass fibres are first made into a slurry or paste, which forms the aspect of the invention, with a liquid compatible with the plastics-forming ingredients or with all or a part of one or more of the ingredients. The invention includes a novel form of chopped glass fibres formed from glass strand bound with a size containing as the main ingredient one component of a plastics-forming mixture or a derivative thereof. It also includes apparatus for mixing the glass fibre paste or slurry with plastics-forming ingredients by impingement mixing. 
     The invention is of special use for reinforcing with glass fibres plastics articles, especially polyurethane plastics articles, formed by a Reaction Injection Moulding (RIM) process.

This invention relates to a process for the manufacture of plasticsarticles containing glass fibres, to the articles so produced and toapparatus for carrying out the process. The invention also relates to aglass fibre paste or slurry for use in the process and to a novel formof glass fibre.

At the present time there is much interest in processes for themanufacture of plastics articles reinforced with glass fibres and, inparticular, processes which comprise dispensing into a mould or betweenmould surfaces or onto a former a mixture of reactive plastics-formingingredients obtained by mixing by impingement the liquid ingredients.One such process is the "reaction injection moulding" (RIM) process usedfor the manufacture of car parts, such as fascia panels and otherinternal and external car fitments, made from polyurethanes andpolyester and epoxy resins. The RIM process is well known and documentedand equipment is commercially available for its use.

Although glass fibres, in most forms, are readily incorporated intoplastics-forming ingredients which are mixed using low pressuremechanical mixing equipment, this is not so where impingement mixing isused. Because the ingredients are necessarily injected at high velocitythrough restricted nozzles into the mixing head to ensure goodimpingement mixing, the length and diameter of the fibres and their"loading", that is the quantity of fibres suspended in the ingredients,is limited. In practice, conventional chopped strand fibres have notbeen found suitable so milled fibres are used instead.

Chopped strand fibres are the fibres produced by chopping into desiredlengths strands of glass filaments which are adhered together with abinder or size. It is necessary to gather, usually a few hundred, ofthese filaments into cohesive strands since the glass filaments are toofine to chop individually. Thus chopped strands are small bundles ofperhaps 100 to 1600 short filaments. The binder, commonly know as a`film-former`, is often polyvinyl acetate.

Milled fibres are the fibres produced when glass fibre strands are`hammer-milled` instead of chopped. The hammer milling process breaksdown the strands into individual filaments of differing lengths. Theiraverage length is normally less than 1 mm and often as low as 0.1 mm.They differ from very short chopped fibres in that the filaments in abundle of chopped fibres are substantially all of the same length.Milled fibres are more expensive to produce than chopped strand fibresand their manufacture less attractive because of the nuisance caused bya significant amount of fine glass dust produced during milling.

For these reasons and because longer fibres tend to provide betterreinforcement, a method by which chopped strand fibres can beincorporated into plastics articles and especially urethane plasticsarticles, using impingement mixing is much sought after.

According to the present invention we provide a process for themanufacture of glass fibre-reinforced plastics articles, especiallythose made using impingement mixing of the plastics-forming ingredients,which comprises mixing together liquid plastics-forming ingredients andchopped glass fibres in filamentary form, introducing the mixture soobtained into a mould or between mould surfaces or onto a former andallowing the mixture to react and set. The invention also includes thearticles so produced. While the process of the invention is ofparticular value in the manufacture of plastics articles made usingimpingement mixing techniques, we have also found that plastics articlesmade by other methods show improved physical properties when reinforcedwith chopped glass fibres in filamentary form rather than withnon-filamentised glass fibres.

The types of plastics which can be used to make the articles of theinvention include epoxy and unsaturated polyester resins, phenolic foamsand urethane plastics. The ingredients from which they are formed arewell known to the skilled worker in the relevant plastics field. Ofespecial interest to us are urethane plastics formed from apolyisocyanate and a polyol. These vary in type depending inter alia onthe particular polyisocyanate and polyol chosen and the relativequantities used and other ingredients present which may include"chain-extenders", "cross-linking agents" and "blowing agents" toproduce foamed materials. Water may be used as a blowing agent. Thisreacts with the polisocyanate to form a polyurea and carbon dioxidewhich "blows" the plastics material into a foam. Thus the term urethaneplastics materials, as it is hereinafter used, is taken to includematerials which contain a substantial proportion of polyurea groups, aswell as urethane groups, and also isocyanurate groups formed bytrimerisation of the polyisocyanate with a suitable catalyst.

Conveniently the glass fibres are mixed with the plastics-formingingredients as a paste or slurry supported in a liquid compatible withthe plastics-forming ingredients or in all or in part of one or more ofthe liquid ingredients. By a liquid compatible with the plastics-formingingredients we mean any liquid which can be mixed with theplastics-forming ingredients and which allows the ingredients to reactand set to form a plastics article while remaining dispersed in theingredients. It may be a liquid inert to the plastics-formingingredients, such as a silicone.

Alternatively the paste or slurry is formed from a liquid which itselfforms part of the plastics-forming ingredients. For example, in the caseof a polyester resin, all or part of the polyester component may be usedto form the paste or slurry. With an epoxy resin, the polyepoxidecomponent may be used and with a phenol-formaldehyde resin the resolecomponent may be used.

In the case of polyurethanes, all or part of the polyol is convenientlyused but the isocyanate component may be used and it is also envisagedthat the chopped fibre glass may be supported in both components. Thepolyol or polyisocyanate from which the paste or slurry is formed may bethe same or different from the rest of the polyol or polyisocyanateused.

Chopped glass fibres may be obtained in filamentary form by, forexample, shaking them in caustic soda solution until they swell andseparate into individual filaments. More conveniently, however, we havefound that chopped glass strands can be filamentised in the making ofthe paste or slurry. By "filamentised" we mean the bundles of fibreswhich constitute the chopped strands are separated substantially intotheir individual filaments.

The case with which the fibres can be filamentised will depend, interalia, on the size or `film-former` used to bind the strands. Ideally itsadhesive qualities will be sufficient only to prevent the strandsseparating into their component filaments prior to mixing into the pasteor slurry, but must obviously be sufficiently effective to preventfilamentisation during the chopping process. Good filamentisation isachieved when the `film-former` which binds the filaments is soluble inthe paste or slurry medium so that the filaments are efficiently`wetted-out`. In one embodiment the `film-former` consists substantiallyof the liquid used as the paste or slurry medium or a derivativethereof.

Thus in a further aspect of our invention we provide a novel form ofchopped fibre glass made by forming into strands filamentary glass whichhas been coated with a size containing, as the main ingredient, onecomponent of a plastics-forming mixture, or a derivative thereof, andchopping the strands into short lengths.

For urethane plastics articles, we have found that good results areachieved when the liquid for making the paste or slurry is a polyol,especially a high molecular weight polyol (M.W. 200-6000), and when thesize used in making the chopped strands contains a polyol or polyolderivative as the main binder ingredient. In this case, the liquid usedto make the paste or slurry will preferably be a polyol which is thesame as that from which the size is derived or a polyol havingchemically similar component groups. In particular we would mentionpolyether polyols, especially polyalkylene oxide polyols of molecularweight of from 200 to 6000, but other polyols, for example polyesterpolyols of molecular weight of from 200 to 3000, may also be used.

Depending on the length and thickness of the filamentary fibres, thefibre glass paste or slurry will normally have a loading of up to 75%;that is it will contain up to 75% by weight of glass fibre on thecombined weight of the glass fibre and liquid medium. At a loading of80%, fibres approximately 3 mm long and 15 μ thick will give anunworkable paste in a polyol used for microcellular elastomers. At 40%,the paste has a "toothpaste" consistency which retains this consistencyon extrusion from a nozzle. At 50% and higher loadings the "toothpaste"consistency tends not to be retained on extrusion. In one particularembodiment of the process of the invention there is used a fibre glasspaste in which the amount of liquid present is such that it does notseparate from the paste to form a discrete layer. These pastespreferably have a loading of 40 to 50%. At 10% loading the liquid mediumusually separates from the paste so that at lower loadings slurries willbe obtained. Typical slurries of 1.5 mm long fibres will have a loadingof 5 to 20%.

The filamentary glass fibres which may be used will normally be between0.5 and 100 mm in length. Particularly useful are those in the range of1.5 to 3 mm in length. Fibres of mixed lengths may also be used. Thefilamentary fibre thickness will normally be in the range of from 5 to25 μ and is preferably in the range of from 13 to 17 μ.

Other particulate filler materials may be added to the fibre paste. Inparticular we would mention inorganic powdered materials such as chalk.

Thick pastes are conveniently prepared by mixing the fibres and liquidin a `dough mixer`. Thinner pastes and slurries can be prepared usingconventional paddle stirrers.

The paste or slurry can then be mixed with the other plastics-formingingredients and the mixture so obtained injected into the mould. It isalso envisaged that the mixture can be dispensed, utilising impingementmixing techniques, between mould surfaces in the manufacture, continuousor otherwise, of, for example foam panels and particularly urethane foampanels, especially those having a high isocyanurate content. Such panelsare of especial interest in the building industry for insulationpurposes. In addition to reinforcing the foam, the glass fibres help tomake the foam more fire resistant.

It may be possible to use conventional RIM process machinery for mixingand dispensing the plastics-forming mixture but this will depend interalia on the loading of the paste or slurry, the length of fibres and theoverall viscosity. As a guide, a slurry of up of 5% loading of 3 mmfilamentary chopped fibre in a polyol suitable for microcellularelastomers can be dispensed in conventional equipment as can similarslurries of up to 12% loading of 1.5 mm filamentary chopped fibre andpossibly up to 2% loading of 6 mm chopped fibre. Conveniently theapparatus hereinafter described, which is a mixing and dispensing gunand which also forms part of the present invention, can be used.

Thus according to yet a further aspect of our invention we provideapparatus for mixing and dispensing liquid material and a paste orslurry of fibrous or other particulate filler material, which comprisesa mixing chamber having an outlet, an inlet constructed for the supplyat low velocity to the chamber of paste or slurry, and one or moreinlets constructed for the supply at high velocity to the chamber ofliquid material; the inlets being arranged to enable the liquid materialto impinge on the paste or slurry to effect mixing.

To obtain good mixing of plastics-forming ingredients, it is necessarythat the liquid material impinges on the paste or slurry at highvelocity to create high turbulence in the mixing chamber. The liquidwill need to be fed to the chamber under high pressure, the exactpressure depending, inter alia, on the viscosity of the liquid material.The high velocity inlet or inlets will be sized according to thepressure and quantity of material to be delivered.

Because of the higher viscosity of the paste or slurry, relatively highpressures will be needed to obtain low velocity flow into the mixingchamber. Here too, the low velocity inlet will be sized according to thepressure and quantity of paste to be delivered.

Suitably, the outlet is positioned at a forward end of the chamber, thelow velocity inlet at a rearward end and the high velocity inlet orinlets intermediate the forward and rearward ends. Normally there willbe two high velocity inlets, and preferably two pairs of such inlets,diametrally opposed and directed substantially at right angles to theline of flow of paste or slurry from the low velocity inlet to theoutlet.

The low velocity inlet may be shaped in a particular way to suit thedesired distribution of the paste or slurry in the mixing chamber. Forexample, it may be shaped to give a ribbon of paste or it may take theform of an annular opening around the circumference of the chamber.

In a preferred embodiment there is provided a plunger whose forward endis reciprocable within the chamber between an open position rearward ofthe high velocity inlet or inlets and a closed position forward of thehigh velocity inlet or inlets and a passage in the plunger whichcommunicates with the chamber when the plunger is in the open positionand which forms the low velocity inlet.

To prevent clogging of the chamber by material left after a dispensingoperation, the forward end of the plunger is preferably made flush withthe outlet end of the chamber when in the closed position.

The plunger can be reciprocated within the chamber by any suitablemeans. Conveniently, however, its rearward end is attached to a pistonwhich itself is reciprocable in a cylinder and which, in turn,reciprocates the plunger. The piston may be operated hydraulically or bygaseous pressure.

The low velocity inlet is connectable to a device for supplying thepaste or slurry of fibrous or other particulate filler material. Onesuch device comprises a paste pumping cylinder and a paste pumpingpiston reciprocable within the cylinder, the cylinder having an outletfor connection with the low velocity inlet of the mixing and dispensingapparatus and an inlet for the supply of paste.

The paste pumping piston is preferably operated hydraulically ormechanically. Better control over the output rate of the paste pump isobtained using mechanical means, for example, an electric motor andcrank mechanism.

The apparatus of the present invention will now be further described byway of example, with reference to the accompanying drawings in which

FIG. 1 is a diametral elevational section through part of a mixing anddispensing gun in a closed position;

FIG. 2 is the same section as FIG. 1 except that the gun is in an openposition;

FIG. 3 is a diagrammatic view of the gun shown in FIGS. 1 and 2connected to a device for supplying to the gun a paste of fibrous andother particulate material; and

FIGS. 4 and 5 are diametral elevational sections through differentmixing and dispensing guns.

In FIGS. 1 and 2, a gun 10 comprises a chamber 11 having an outlet 29,and a plunger 12, within said chamber, which is attached to a piston 13housed in a cylinder 14. The plunger 12 is shown, in a closed positionin FIG. 1 and in an open position in FIG. 2. The cylinder 14 isconnectable to a supply of hydraulic liquid (not shown) to whichpressure can be applied. A seal 19 prevents hydraulic liquid escapingbetween the piston 13 and cylinder 14. High velocity inlets 15 and 16provide means by which liquid ingredients can be supplied to the chamber11. A passage 17, which forms a low velocity inlet in the pluner 12extends through to the piston 13 into a duct 18 of a larger bore and isconnectable to a device (not shown in FIG. 1) for supplying fibrous orother particulate material to the chamber.

In FIG. 3, a device for supplying a paste or slurry of fibrous and otherparticulate material to gun 10 comprises a paste pumping cylinder 20, apaste pumping piston 21 operated within cylinder 20 by a hydraulicdevice (not shown), a paste feed tank 22 connected to cylinder 20 atinlet 23 via a valve 24 and a short flexible hose 25 which connectscylinder 20 at outlet 26 through valve 27 to the passage (not shown) inthe piston 13 of gun 10.

The operation of this apparatus will now be described in relation to themixing and dispensing of urethane plastics-forming ingredients but itwill be understood that it can similarly be used with otherplastics-forming ingredients.

In one method of using the apparatus with urethane plastics-formingingredients, polyol and polyisocyanate components are circulated at highpressure through a recirculation system provided in the gun (not shown)while the plunger is in the closed position. At this stage valves 24 and27 will be closed and during normal operation the line from the pastepumping cylinder 20 through to the forward end of the passage 17 in theplunger 12 will be full of paste.

When it is desired to mix the urethane plastics-forming ingredients andpaste and to inject the mixture so formed into the mould, the outlet ofthe chamber 11 is positioned at the mould opening and the plunger ismoved to the open position by the hydraulically operated piston 13actuated by a trigger (not shown). High velocity inlets 15 and 16, forthe polyol and polyisocyanate respectively, are opened, and there-circulation systems closed so that streams of these ingredients areinjected under high pressure at high velocity into the chamber 11. Insynchronisation with the retraction of the plunger to the open positionand the opening of inlets 15 and 16, valve 27 is opened and pastepumping piston 21 is actuated to force paste from the pumping cylinder20, which has previously been primed with paste from the feed tank 22,into the mixing chamber at low velocity. The polyol and polyisocyanatestreams impinge on the paste in the mixing chamber wherein the threeingredients are intimately mixed. After a predetermined amount of themixed ingredients has been dispensed from the gun, the trigger isreleased and the plunger is moved forward to the closed position to cutoff supplies of the polyol and polyisocyanate to the chamber 11. As theplunger moves forward valve 27 closes to stop the paste flow. Valve 27is so positioned and operated that there is a slight exudation of pastefrom the forward end of the plunger when it has reached the closedposition. This purges the chamber and keeps the forward end of theplunger clear of the urethane plastics forming ingredients at the end ofeach dispensing operation.

When the mixture has been dispensed, the paste pumping cylinder isautomatically recharged. Thus valve 24 opens and the paste pumpingpiston 21 returns slowly to its starting position drawing in paste fromthe feed tank. Valve 24 then closes and the device is ready for the nextoperation.

A screw type pump may be used as an alternative to the cylinder 20 andpiston 21 of FIG. 3. In this case, valves 24 and 27 are omitted and thescrew pump is started to introduce the paste into the mixing chamber asthe plunger 12 is withdrawn. At the end of the shot the screw pumppreferentially continues to operate for a brief period in order toobtain the small exudation of paste from the forward end of the plungerin the closed position.

Guns for injecting urethane plastics-forming ingredients which have arecirculation facility for the polyol and polyisocyanate components anda hydraulically operated plunger are well known and mechanical featuresused on those guns may be adapted for use on the apparatus of thepresent invention.

Modifications of the apparatus are shown in FIGS. 4 and 5.

In FIG. 4, a mixing chamber 36 has an outlet 37 and diametrally opposedhigh velocity inlets 38 and 39. Low velocity inlet 31 in plunger 32 isribbon-shaped in cross section (one edge of the `ribbon` is shown) andcommunicates with a diametral passage 33. In the open position, passage33 registers with ducts 34 and 35 connectable to a device for supplyingthe paste or slurry.

In FIG. 5, a low velocity inlet 40 comprises an annular opening aroundthe rearward end of chamber 36¹ and communicates with a supply passage(not shown).

It is not necessary that the isocyanate and polyol components are eachinjected through one of the high velocity inlets as described. It ispossible, for instance, to inject all of the polyol or all of theisocyanate as a slurry with the fibrous material and to inject twostreams of the other reactive ingredient from the twin high velocityinlets. It will be evident from this that other variations are alsopossible.

Other features of known mixing and dispensing equipment may be adaptedfor use with the apparatus of the present invention. For example, theoutlet 29 (FIGS. 1 and 2) or 37 (FIG. 4) may be connected to a second,larger bore mixing chamber, the direction of flow through which isinclined, preferably at 90°, to that from the first into the secondchamber. This feature of a second mixing chamber is described in UKPatent Specification No. 1501814. Such a device facilitates mixing of avolatile foaming agent with the plastics-forming ingredients at thelower pressure of the second chamber. Also, a plunger in the secondchamber can usefully be employed to remove reactive ingredients from theend of the plunger in the first mixing chamber at the end of a shot.

Other ingredients may be introduced with the isocyanate or polyol orthrough a separate inlet into the mixing chamber.

Preferably the gun is mounted on the mould and the paste feed devicekept as close as possible to keep the pressure drop to a minimum. Forthe same reason, the bore of the duct 18 is as large as is practical andthe relativey small bore of passage 17 as short as possible.

A typical output rate for urethane plastics-forming ingredients is 100kg/min. The amount of paste required to incorporate 10% by weight offibres and other filler material (dry weight) on the weight ofplastics-forming ingredients will be about 13.5 kg/min allowing for theliquid present. If the paste density is about 2.2 gm/cm³, then for a 6mm diameter passage in the plunger, the output velocity required is 360cm/sec and for a 1 cm diameter passage, 130 cm/sec.

Ideally, the diameter of the passage 17 is the same as the mean fibrelength or greater. It is unlikely that good results will be obtained ifthe diameter is less than one tenth the mean length of the fibre. On theother hand, the bore should not be so wide that inefficient impingementmixing of the polyol and isocyanate results.

The method and apparatus of the invention may be used for makingplastics articles in a batch moulding process or may be adapted forcontinuous or semi-continuous moulding, for instance, in continuouslamination processes and in particular in the continuous lamination ofrigid urethane foam products with paper and rigid facings. In acontinuous process a self-cleaning facility on the gun would not benecessary as the paste feed would be continuous. The paste could besupplied continuously by a double acting pump or two linked singleacting pumps working in opposite phases. Of course, these could also beused where a single large `shot` of the foam-forming ingredients isrequired.

The invention is further illustrated by the following examples in whichparts and percentages are by weight unless otherwise stated.

EXAMPLE 1

A 40% paste was prepared by mixing together in a dough mixer 40 parts ofchopped fibre glass strands (mean length 3 mm) bound with a sizecontaining, as the main ingredient, a polyol derivative and chopped fromfibre glass roving obtainable from Fiberglass Limited, ReinforcementsDivision, St. Helens, Merseyside, UK under the name WX 6012 ExperimentalRoving, and 60 parts of a polyether triol which is a 15% ethylene oxidetipped oxypropylated glycerol (MW approximately 5300: OH value 32 mgKOH/g: 75% primary OH groups).

The paste was extruded through an 8 mm long tube having an internaldiameter of 3.5 mm under pressure. The paste extruded rapidly retaininga "toothpaste" consistency.

EXAMPLE 2

The procedure of Example 1 was repeated except that only 40 parts of thepolyol were used to give a paste loading of 50%. Again the pasteextruded rapidly but did not retain its "toothpaste" consistency.

EXAMPLE 3

The procedure of Example 1 was repeated except that only 13.3 parts ofthe polyol were used to give a paste loading of 75%. The paste extrudedrapidly but did not retain its paste-like form.

COMPARATIVE EXPERIMENTS

The procedure of Example 1 was repeated except that no polyol was used.The dry fibre could not be extruded even through a 5 mm bore tube. Thefibre when mixed with 10% polyol could not be extruded through the 3 mmor 5 mm bore tube.

EXAMPLE 4 Polyurethane Microcellular Elastomer (i) Comparative control:no fibreglass

A polyol blend, prepared by stirring together the ingredients listedbelow was mixed for 5 seconds with 101.7 parts of an MDI(diphenylmethane diisocyanate) blend of NCO value 26%. The reactingmixture was rapidly poured into an open metal mould (dimensions 20 cm×10cm×3 mm) preheated to 50° C. and the mould was sealed. After 5 minutes,the moulded microcellular elastomer so obtained was removed from themould. After ageing for 48 hours physical tests were carried out and theresults are shown in Table 1.

    ______________________________________                                        Polyol Blend             parts                                                ______________________________________                                        Polyol (ethylene oxide tipped propylene-                                      oxide Diol/Triol Mix) OHV 30                                                                           100                                                  1,4,Butane Diol          25                                                   DABCO 33 LV (T.M.)       0.7                                                  Dibutyl Tin Dilaurate    0.05                                                 Water                    0.12                                                 ______________________________________                                    

(ii) Comparative Experiment: non Filamentised Glass

The procedure of Example 4(i) was repeated except that 5 parts of 3 mmchopped glass strand (FS 52 ex Scandinavian Glass Fibre Ltd) werepremixed into the polyol blend prior to mixing with the isocyanate. Theglass fibre was clearly visible in the polyol mixture as cohesivestrands and little effect on viscosity of the addition was noted.

Physical test results are shown in Table 1.

(iii) Filamentised Chopped Glass

The chopped glass fibre strand of Example 4(ii) was treated in thefollowing manner to break down the strands into individual filaments.

The chopped strands (25 gm) were shaken in 200 ml of a solution of 5%caustic soda in water. The fibre bundles immediately swelled andseparated into individual filaments. The very viscous slurry was thenallowed to stand for 3 days, after which time the 3 mm filaments werefiltered off, washed alkali free with water and finally washed withacetone and dried at 80° C. for 2 hours.

This dried, filamentised glass fibre was used to prepare a microcellularpolyurethane elastomer by the procedure of Example 4(i) but adding 2.5parts of the pretreated fibre to the polyol blend.

It was found impracticable to add any more than this because of thelarge increase in viscosity caused by the filamentised glass.

Physical test results are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                        Example No.  4(i)      4(ii)      4(iii)                                      ______________________________________                                        Glass Content                                                                               0        2.2        1.1                                         (% w/w overall)                                                               Glass Type   --        3mm Strand 3mm                                                                           Filament                                    Density (Kg m.sup.-3)                                                                      930       925        907                                         Hardness (Shore D)                                                                          47       49          53                                         Tensile Strength                                                                           12,500    9,700      12,100                                      (KN m.sup.-2)                                                                 Elongation at Break                                                                        160       75         105                                         Flexural Modulus                                                                           214       224        266                                         (MPa)                                                                         Sag Test (120° C.                                                                   35.6mm    27.9mm     15.2mm                                      30 min, 100mm                                                                 Overhang)                                                                     Coefficient of Linear                                                                      1.3 × 10.sup.-4                                                                   1.02 × 10.sup.-4                                                                   0.82 × 10.sup.-4                      Thermal Expansion                                                             (°K.sup.-1)                                                            ______________________________________                                    

NB. In the microcellular elastomer of Example 4(ii) the fibre strandswere visible in the moulded surface and in the broken ends of thetensile strength test pieces. No fibres were visible to the naked eye inExample 4(iii).

EXAMPLE 5 Polyurethane Microcellular Elastomer (i) ComparativeExperiment: Hammer-Milled Glass

The procedure of Example 4(i) was repeated using 20 parts ofhammer-milled glass (Type 731 CA 1/16" ex. Owens Corning Fibreglass Ltd)premixed into the polyol blend. Results are shown in Table 2.

(ii) Comparative Experiment: Hammer-Milled Glass (High Level)

The procedure of Example 5(i) was repeated but using 60 parts of thehammer-milled glass. Results are shown in Table 2. The microcellularelastomer had a very porous surface.

(iii) 1.5 mm chopped, filamentised glass

The procedure of Example 4(i) was repeated but incorporating 20 parts ofa 1.5 mm chopped glass strand (chopped from Type WX 6012 ExperimentalStrand ex Fibreglass UK Ltd). The fibre filamentised rapidly on stirringinto the polyol blend. No visible sign of the fibres could be observedin the resultant microcellular elastomer. Results are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                        Example No.       5(i)     5(ii)    5(iii)                                    ______________________________________                                        Glass Content (% w/w overall)                                                                   8.1      21       8.1                                       Glass Type        hammer-  hammer-  1.5 mm                                                      milled   milled   Chopped                                                                       filament                                  Density (Kg m.sup.-3)                                                                           900      970      860                                       Hardness (Shore D)                                                                              53       57       50                                        Tensile Strength (KN m.sup.-2)                                                                  10,300   12,500   18,100                                    Elongation at Break (%)                                                                         70       30       10                                        Flexural Modulus (MPa)                                                                          440      750      690                                       Sag Test (120° C., 30 min 100mm                                                          2.5mm    2.5mm    1.3mm                                     overhang)                                                                     Coefficient of Linear Thermal                                                                   0.82     0.30     0.42                                      Expansion                                                                     ______________________________________                                    

EXAMPLE 6 Polyurethane Microcellular Elastomer (i) Comparative Control:no fibreglass

Using a Krauss Maffei 40/80 RIM machine equipped with piston dosingsystem on the polyol side, and a temperature controlled (50° C.) mouldof dimensions 1 meter×30 cm×4 mm, test sheets were made from thefollowing formulation:

    ______________________________________                                                          parts                                                       ______________________________________                                        Polyether triol used in Ex. 1                                                                     100                                                       Ethylene Glycol     21                                                        DABCO (T.M.)        0.7                                                       Dibutyl Tin Dilaurate                                                                             0.1                                                       MDI blend used in Ex. 4(i)                                                                        121                                                       ______________________________________                                    

The physical properties are shown in Table 3.

(ii) Comparative Experiment: Hammer-Milled Glass

The procedure of Example 6(i) was repeated but incorporating 63.5 partsof hammer-milled glass (Type 731CA ex Owens Corning Fiberglass Ltd) intothe polyol blend. Test results are shown in Table 3.

(iii) Filamentised Glass

The procedure of Example 6(ii) was repeated but incorporating 13.3 partsof 1.5 mm chopped fibreglass strand (Type WX 6012 ex Fibreglass UK Ltd).The fibreglass filamentised on stirring into the polyol blend. Physicaltest results are shown in Table 3.

Microscopic examination showed no unfilamentised bundles.

                  TABLE 3                                                         ______________________________________                                        Example No.      6(i)      6(ii)    6(iii)                                    ______________________________________                                        Glass Content (% w/w                                                                           0         20       5                                         overall                                                                       Glass Type       --        H.M.     1.5                                                                           Chopped                                                                       Filament                                  Density (Kg m.sup.-3)                                                                          1170      1020     1020                                      Hardness (Shore D)                                                                             61        55       60                                        Tensile Strength (KNm.sup.-2)                                                                  23600     12800    19000                                     Elongation at Break (%)                                                                        115       30       35                                        Flexural Modulus (MPa)                                                                         310       560      650                                       Sag. Test. (120° C., 60 min,                                                            9.1 mm    1.3 mm   0                                         100 mm overhang)                                                              Coefficient of Linear                                                                          130×10.sup.-6                                                                     33×10.sup.-6                                                                     35×10.sup.-6                        Thermal Expansion (° K.sup.-1)                                         ______________________________________                                    

EXAMPLE 7 Structural (High Density Rigid) Polyurethane Foams (i)Comparative control: no fibreglass

A polyol blend prepared by stirring together the ingredients listedbelow was mixed with 135 parts of a low functionality polymeric MDI andpoured into a metal mould (30 cm×15 cm×1.25 cm) heated to 55° C. toproduce a structural foam test piece. After allowing 48 hrs forcompletion of curing the sample was tested. The test results are givenin Table 4.

    ______________________________________                                        Polyol Blend           parts                                                  ______________________________________                                        Oxypropylated trimethylol propane                                                                    70                                                     (OH value 540 mg kOH/g)                                                       Oxypropylated trimethylol propane                                                                    30                                                     (OH value 360 mg kOH/g)                                                       Silicone L 5420 (ex Union Carbide)                                                                   0.5                                                    Salicylic Acid         0.75                                                   N,N-dimethylcyclohexylamine                                                                          2.7                                                    Water                  0.25                                                   "Arcton" 11 (RTM)      4                                                      ______________________________________                                    

(ii) Comparative Experiment: non-Filamentised Glass

The procedure of Example 7 (i) was repeated except that 12.6 parts of 3mm chopped glass fibre FGCS 1617 (ex Fibreglass UK Ltd) wereincorporated in the polyol blend prior to mixing with the isocyanate.Little increase in viscosity was noted on incorporation of the fibre andthere could be clearly seen discrete bundles of fibres in the polyolblend. Test results are shown in Table 4.

(iii) Filamentised Chopped Glass

The procedure of Example 7(i) was repeated except that 12.6 parts of 3mm chopped glass strand(chopped from WX 6012 Experimental Strand, exFibreglass UK Ltd.) were incorporated in the polyol blend prior tomixing with the isocyanate. Incorporation of the fibre gave a largeincrease in viscosity and upon microscopic examination no fibre bundlescould be detected. Test results are shown in Table 4.

                  TABLE 4                                                         ______________________________________                                        Example No.        7(i)    7(ii)    7(iii)                                    ______________________________________                                        Glass content (% w/w overall)                                                                    0       8.4      8.4                                       Glass Type         --      3 mm     3 mm                                                                 chopped  chopped                                                              strand   filament                                  Density (K gm.sup.-3)                                                                            420     450      440                                       Heat Distortion Temp.                                                                            64      65       92                                        (ASTM D648-56)                                                                Impact Strength (Falling Weight)                                                                 10.1    10.9     14.1                                      (Joules)                                                                      Tangent Modulus of Elasticity                                                                    580     760      890                                       (MPa)                                                                         Stress at Break (MPa)                                                                            16.3    21.5     22.5                                      Strain at break (%)                                                                              7.1     4.5      2.9                                       ______________________________________                                    

EXAMPLE 8 Rigid Polyurethane Foams (i) Comparative Control: nofibreglass

A polyol blend prepared by stirring together the ingredients listedbelow was mixed with 112 parts of polymeric MDI and poured into a squarebox mould (18 cm×18 cm) and allowed to form a free rise rigid foam.After allowing 48 hours for curing, the foam was sliced to obtainsamples 20 mm thick from the inner part of the foam. Test pieces werethen sawn from these 20 mm thick slices. Test results are shown in Table5.

    ______________________________________                                        Polyol Blend               parts                                              ______________________________________                                        Oxypropylated sorbitol     100                                                Ethylene oxide tipped oxypropylated ethylene glycol                                                      5                                                  Silicone L 5420 (ex Union Carbide)                                                                       1.5                                                N,N-dimethylcyclohexylamine                                                                              4                                                  "Arcton" 11 (RTM)          40                                                 ______________________________________                                    

(ii) Comparative Experiment: non-Filamentised Glass

The procedure of Example 8(i) was repeated except that 12 parts of 3 mmfibre glass chopped strand FGCS 1617 (ex Fibreglass UK Ltd) wereincorporated into the polyol blend prior to mixing with the isocyanate.The fibres were clearly visible as discrete bundles in the polyol and nolarge increase in viscosity occurred. Test results are shown in Table 2.

(iii) Filamentised Chopped Glass

The procedure of Example 8(i) was repeated except that 12 parts of 3 mmfibreglass chopped strand (chopped from WX 6012 Experimental Strand, exFibreglass UK Ltd) were incorporated into the polyol blend. The fibrebundles dispersed readily into individual filaments and a largeviscosity increase was noted. Physical test results are shown in Table5.

                  TABLE 5                                                         ______________________________________                                        Example No.       8(i)    8(ii)    8(iii)                                     ______________________________________                                        Glass Content (% overall)                                                                       0       5        5                                          Glass             --      3 mm     3 mm                                                                 Chopped  Chopped                                                              Strand   Filaments                                  Density (kg/m.sup.3)                                                                            31.0    32.6     34.5                                       3 Point Load Test (I.S.O. 1209)                                               Load at Break (N) 21      19       25                                         Deflection at Break (mm)                                                                        12      12       11                                         Bending Modulus (KNm.sup.-2)                                                                    4600    4500     6200                                       ______________________________________                                    

EXAMPLE 9 Epoxy Resin Casting (i) Comparative Control: no fibreglass

A bisepoxide derived from bisphenol A, Epikote* 828 (100 parts),diethylene triamine (12 parts) and γ-butyrolactam (20 parts) were mixedtogether in a cardboard cup using a low speed paddle stirrer. Themixture was then poured into an open metal cavity of dimensions 15 cm×15cm ×2 mm and allowed to set for 2 hours. The casting was then post-curedfor 1 hour at 150° C. Test results are shown in Table 6.

(ii) Comparative Experiment: Non-Filamentised Glass

The procedure of Example 9(i) was repeated except that 4 parts of 3 mmchopped glass fibre FGCS 1617 (ex Fibreglass UK Ltd.) were incorporatedin the mixture. No viscosity increase was observed and the fibre bundleswere clearly visible in the casting.

Test results are shown in Table 6.

(iii) Filamentised Chopped Glass

The procedure of Example 9(i) was repeated except that 4 parts of 3 mmglass strand (chopped from WX 6012 Experimental Strand, ex Fibreglass UKLtd.) were incorporated in the mixture. A large increase in viscositywas noted and the fibres could not be distinguished in the casting. Testresults are shown in Table 6.

                  TABLE 6                                                         ______________________________________                                        Example No.       9(i)   9(ii)     9(iii)                                     ______________________________________                                        Glass type        --     3 mm      3 mm                                                                bundles   filaments                                  Glass Loading (% w/v overall)                                                                   0      3         3                                          Density (Kg/m.sup.3)                                                                            1060   1120      1120                                       Hardness (Shore D)                                                                              86     89        89                                         Flexural Modulus (MPa)                                                                          1070   2370      2730                                       ______________________________________                                    

EXAMPLE 10 Unsaturated Polyester Resin Casting (i) Comparative Control:no fibreglass

Impolex* D1015 polyester resin (obtainable from Imperial ChemicalIndustries Limited, Petrochemicals Division) (100 parts) andmethylethylketone peroxide (1.5 parts) were mixed in a cardboard cupwith a paddle stirrer. The liquid mixture was poured into a metal cavityof dimensions 15 cm×15 cm×2 mm and allowed to set for 2 hours. Thecasting was then post-cured at 150° C. for 1 hour. Test results areshown in Table 7.

(ii) Comparative Experiment: Unfilamentised Glass

The procedure of Example 10(i) was repeated except that 3.0 parts of 3mm chopped glass fibre FGCS 1617 (ex Fibreglass UK Ltd.) wereincorporated in the polyester resin. The chopped strands had littleeffect on viscosity and were clearly visible in the coating. Testresults are shown in Table 7.

(iii) Filamentised Chopped Glass

The procedure of Example 10(i) was repeated except that 3.0 parts of 3mm chopped glass strand chopped from WX 6012 (Experimental Strand, exFibreglass UK Ltd.) were incorporated in the polyester resin. The fibredispersed rapidly and caused a large increase in viscosity. The fibrescould not be distinguished in the casting. Test results are shown inTable 7.

                  TABLE 7                                                         ______________________________________                                        Example No.    10(i)    10(ii)    10(iii)                                     ______________________________________                                        Glass type     --       3 mm      3 mm                                                                strand    filament                                    Glass content (% overall)                                                                    0        2.9       2.9                                         Density (Kg/m.sup.3)                                                                         1216     1240      1200                                        Flexural Modulus (MPa)                                                                       12       25        120                                         Tensile Strength (kN/m.sup.2)                                                                3840     3840      7120                                        ______________________________________                                    

EXAMPLE 11 Polyurethane Microcellular Elastomer (i) Comparative Control:no fibre glass

The procedure of Example (4(i) was repeated except that the mouldingprocess was marginally altered to give an elastomer of slightly higherdensity. Test results are given in Table 8.

(ii) Comparative Experiment: Non-filamentised glass

The procedure of Example 11 (i) was repeated except that 6.6 parts of 3mm chopped glass fibre FGCS 1617 (ex Fibreglass UK Ltd.) wereincorporated into the polyol blend prior to mixing with the isocyanate.Test results are given in Table 8.

(iii) Filamentised Chopped Glass

The procedure of Example 11 (i) was repeated except that 6.6 parts of 3mm chopped glass strand (chopped from WX 6012 Experimental Strand, exFibreglass UK Ltd.) were incorporated into the polyol blend prior tomixing with the isocyanate. Test results are given in Table 8.

                  TABLE 8                                                         ______________________________________                                        Example No.    11(i)    11(ii)    11(iii)                                     ______________________________________                                        Glass Type     --       3 mm      3 mm                                                                strand    filament                                    Glass Concentration                                                                          0        2.8       2.8                                         (% w/w overall)                                                               Density (Kg/m.sup.3)                                                                         1090     1080      1020                                        Hardness (Shore D)                                                                           61       59        60                                          Tensile Strength (KNm.sup.2)                                                                 15,000   11,400    13,000                                      Elongation at Break (%)                                                                      130      70        40                                          Flexural Modulus (MPa)                                                                       290      300       450                                         ______________________________________                                    

Parts (i) and (ii) of Examples 4 to 11 are given for comparativepurposes only and from no part of the present invention.

DISCUSSION OF RESULTS

From Table 1 it will be seen that the use of filamentised 3 mm choppedglass in a microcellular elastomer, in accordance with our invention,produces a product superior to that made with twice as muchunfilamentised 3 mm chopped glass, particularly in respect of theimportant properties of tensile strength, flexural modulus, sag andlinear thermal expansion. Table 8 shows that a similar elastomerreinforced with 3 mm chopped glass filamentised by a different methodgives a superior product to that made with the same amount ofunfilamentised 3 mm chopped glass.

From Table 2 it will be seen that the use of filamentised 1.5 mm choppedglass in the elastomer of Table 1 produces a product superior to thoseproducts made with (a) the same amount, and (b) twice the amount, ofhammer-milled glass.

From Table 3 it will be seen that the use of filamentised 1.5 mm choppedglass in a different elastomer produces a product superior to that madewith nearly four times as much hammer-milled glass.

Table 4 shows that filamentised 3 mm chopped glass in a structural foamgives a product superior to such foams containing non-filamentisedchopped glass of the same length in respect of heat distortion, impactstrength, tangent modulus of elasticity and stress and strain at break.Table 5 shows that in a rigid foam it gives a product superior in a3-point load test.

Tables 6 and 7 show that filamentised 3 mm chopped glass in epoxy resinand unsaturated polyester resin coatings gives products of superiorflexural modulus and, in the case of the polyester resin, superiortensile strength than equivalent products made with non-filamentisedchopped glass.

I claim:
 1. In a process for the manufacture of glass-reinforcedplastics articles which comprises mixing liquid plastics formingingredients together with chopped glass fibres and introducing themixture so obtained into a mould, between mould surfaces or onto aformer and allowing the mixture to set, the improvement which comprisesusing fibres which are:(a) bound with a size which is soluble in aliquid medium; and (b) supported as a paste or slurry in said liquidmedium which is either (i) compatible with said plastics formingingredients or (ii) all or part of one or more of said plastics formingingredients;wherein when said fibres bound with said size are mixed withthe liquid medium for support the fibres disperse readily intoindividual filaments.
 2. Process as claimed in claim 1 in which saidplastics-forming ingredients and said glass fibre paste or slurry aremixed by impingement mixing.
 3. Process as claimed in claim 1 in whichsaid plastics-forming ingredients comprise a polyisocyanate and apolyol.
 4. Process as claimed in claim 3 in which said glass fibres aremixed with said plastics-forming ingredients as a paste or slurrysupported in all or part of said polyol.
 5. A glass fibre paste orslurry suitable for use in the manufacture of glass-reinforced plasticsarticles by mixing liquid plastics forming ingredients together withchopped glass fibres and thereafter introducing the mixture so obtainedinto a mould, between mould surfaces or onto a former and allowing themixture to react and set, which paste or slurry comprises:(a) choppedglass fibre strands in filamentary form and bound with a size which issoluble in a liquid plastics forming medium, and supported as a paste orslurry in (b) liquid medium which is compatible with plastics formingingredients or all or part of one or more of said plastics formingingredients,said fibres being characterized further by their substantialseparation into individual filaments when mixed with said liquid medium.6. A paste or slurry as claimed in claim 5 in which said liquid formaking said paste or slurry is a polyol and said glass fibres arechopped from glass strands bound with a size which contains a polyol orpolyol derivative as the main binder ingredient of said size.
 7. A pasteor slurry as claimed in claim 6 in which said liquid for making saidpaste or slurry is a polyol which is the same as that from which saidsize is derived or a polyol having chemically similar component groups.8. A paste or slurry as claimed in claim 5 in which said paste or slurrycontains glass fibre in an amount not greater than 75% by weight on thecombined weight of glass fibre and liquid used for making said paste orslurry.